This invention relates to processes and materials for the formation of films on semiconductor substrates, and in particular to chemical vapor deposition processes and materials for the formation of such films.
The manufacture of semiconductor devices often requires the deposition of thin dielectric films upon semiconductor wafers. The most commonly used process is chemical vapor deposition (CVD), using silane, disilane, or tetraethyl orthosilicate precursors for the formation of silicon-based films. Precursors for silicon nitride films in particular include tertiary amines, mixtures of dichlorosilane with ammonia, mixtures of silane with ammonia, and mixtures of diethylsilane with ammonia. Oxynitrides can be obtained by addition of nitrous or nitric oxide. These methods suffer from various drawbacks, such as high hydrogen content in the deposited films, use of chlorosilane precursors (which results in the formation and deposition of ammonium chloride), and use of pyrophoric gases. U.S. Pat. Nos. 5,874,368 and 5,976,991 to Laxman et al. disclose a process for the low pressure chemical vapor deposition (LPCVD) of silicon dioxide or silicon nitride films using bis(tert-butylamino) silane. However, LPCVD is disadvantageous in that it generally requires high furnace temperatures exceeding 500xc2x0 C. Higher furnace temperatures can be incompatible with other steps of the semiconductor manufacturing process such as middle and back end of line (MOL and BEOL) processing.
Alternatives to LPCVD include plasma-enhanced chemical vapor deposition (PECVD) and high density plasma chemical vapor deposition (HDPCVD), both of which may be executed at temperatures less than about 500xc2x0 C. With silane precursors, however, these processes can result in less than complete sidewall and/or bottom step coverage, particularly for high aspect ratio gap fill applications. There accordingly remains a need in the art for improved chemical vapor deposition precursors and processes for silicon nitride and oxide films that operate at lower temperature and that provide films with improved properties and improved coverage.
A method for depositing a silicon nitride or oxynitride film on a semiconductor substrate comprises placing the substrate in the presence of plasma energy, and contacting the substrate with a reactive gas composition comprising nitrogen-containing compounds of the formula (Rxe2x80x94NH)2SiX2. The temperature of the substrate may be maintained at less than about 500xc2x0 C.
An alternative preferred embodiment comprises placing a semiconductor substrate in the presence of high density plasma energy; and contacting the substrate with a reactive component comprising bis(tert-butylamino)silane and other optional reactants, optionally at a substrate temperature of less than about 450xc2x0 C. The method results in higher-quality films that are compatible with lower temperature processing requirements.